CERN’s ALICE collaboration has successfully detected the nuclear transmutation of lead into gold. The process, witnessed during near miss lead–lead collisions at the Large Hadron Collider (LHC), has achieved what medieval alchemists could only dream of. Though fleeting and microscopic, the event marks a measurable moment in experimental physics where gold was genuinely produced from lead nuclei.
In a study published in Physical Review Journals, the ALICE team revealed that ultraperipheral collisions between heavy nuclei, encounters where the nuclei pass close to each other but do not collide directly, produced electromagnetic fields powerful enough to knock protons out of lead atoms. The result included trace formations of thallium, mercury, and in rare instances, gold.
The transmutation occurred as 82 proton lead nuclei, accelerated to 99.999993 percent the speed of light, moved past each other in the vacuum chamber. At such velocities, the electromagnetic field surrounding each nucleus becomes compressed into a thin, intense pulse of photons, perpendicular to the direction of motion. These fields interact with opposing nuclei through photon–photon and photon–nucleus interactions.
In this case, photon-induced electromagnetic dissociation took place. A high-energy photon interacted with a lead nucleus and excited it, causing vibrations strong enough to eject protons and neutrons. Since gold has 79 protons, the removal of three protons from lead results in the formation of a gold nucleus. This interaction is now measured and verified.
While the concept of making gold from other materials has existed for centuries, prior laboratory attempts focused on bombarding atoms with neutrons or protons inside nuclear reactors or particle accelerators. These efforts were inefficient, generated radioactive waste, and created minuscule yields. ALICE has now demonstrated a different method, one that relies on the intrinsic properties of heavy ions and electromagnetic fields at extremely high speeds.
To quantify these transmutations, the ALICE collaboration used Zero Degree Calorimeters (ZDCs), detectors designed to count particles emitted at small angles relative to the beam line. These detectors measured the number of interactions that resulted in the emission of one, two, or three protons, each accompanied by at least one neutron. The three-proton signature correlates with the creation of gold nuclei.
The numbers are striking. During periods of active lead–lead interaction, the ALICE experiment recorded an average of approximately 89,000 gold nuclei being formed every second. However, this was a small fraction compared to the rates of thallium and mercury production, which were more common outcomes of these nuclear processes.
Despite the high rate of formation, the practicality of this gold production remains nonexistent. The nuclei produced are highly energetic and short-lived. The gold formed does not exist as a stable element but rather as a fleeting atomic configuration that travels rapidly outward before disintegrating on contact with LHC infrastructure. These fragments include protons, neutrons, and other subatomic particles. The gold exists for mere fractions of a second.
Over the span of Run 2, which occurred between 2015 and 2018, it is estimated that the major experiments at the LHC collectively produced around 86 billion gold nuclei. In terms of physical mass, this amounts to about 29 picograms, or 2.9 times ten to the negative eleven grams. This is an almost unimaginably small quantity, far below the threshold needed for visible material accumulation.
Even with the increase in beam luminosity and performance enhancements during Run 3, the total amount of gold produced remains vanishingly small. The upgraded systems may now generate nearly twice the gold as during Run 2, but the difference remains negligible in any practical context. The total remains in the range of particles, not visible material.
The importance of this experiment lies not in the value of the gold created but in what the process reveals about nuclear physics. These transmutation events help refine models of electromagnetic dissociation, a fundamental aspect of particle physics. They also provide critical data for understanding beam loss mechanisms, which are vital for maintaining the safe and efficient operation of high-energy particle accelerators.
Precise modeling of how heavy ions lose energy and fragment under various conditions is essential for designing collimators and managing beam dynamics. When heavy ion beams degrade or shed particles, those fragments can damage sensitive equipment. Understanding how and when those losses occur enables more accurate predictions, and improves the lifetime and safety of experimental hardware.
Marco Van Leeuwen, spokesperson for the ALICE collaboration, noted the sensitivity of the experiment’s detectors. He emphasized their ability to register both high-energy collisions producing thousands of particles and the subtle signals from near misses where only a few particles are emitted. This dual capability underscores the precision and versatility of the ALICE detector system.
Uliana Dmitrieva of the collaboration stated that this is the first time electromagnetic nuclear transmutation events have been identified and systematically measured at the LHC. The unique properties of the ALICE ZDCs enabled the collaboration to not only observe but also analyse these fleeting nuclear signatures in detail. This confirms the reality of photon-driven gold formation from lead nuclei at high energy scales.
John Jowett, also of the ALICE team, highlighted the broader implications for future accelerator technologies. Beam losses resulting from electromagnetic dissociation are a known limitation in current machines. These losses must be carefully modeled and mitigated to protect the infrastructure and extend operational lifespans. Studies like this provide new insight into these mechanisms, aiding the design of future facilities such as the proposed Future Circular Collider (FCC).
The result also ties into a broader understanding of how high-energy environments influence atomic structure. The processes observed mirror natural conditions found in certain astrophysical phenomena, such as neutron star collisions or supernovae, where heavy elements are formed. Although on a smaller scale, the LHC experiments mimic aspects of these cosmic events, offering a controlled environment to test nuclear theories.
This research also reinforces the flexibility of experimental physics in probing classical questions through modern technology. The dream of chrysopoeia, once dismissed as pseudoscience, now finds partial fulfilment through rigorous application of quantum mechanics and particle acceleration.
Though the product will never be mined or minted, the concept has moved from folklore to lab bench. This marks a shift from symbolic transformation to one grounded in precision measurements and peer-reviewed data. The gold may be transient, but the data extracted is enduring.
ALICE’s detection of gold formation from lead through electromagnetic dissociation stands as a technical achievement, not a commercial one. It validates theoretical models, advances understanding of beam physics, and contributes to the overall efficiency and safety of high-energy experiments. It also serves as a reminder that what was once a philosophical ideal can now be explored with instruments calibrated to subatomic precision. The transformation may not enrich anyone’s coffers, but it undeniably enriches science.
Source:
https://www.home.cern/news/news/physics/alice-detects-conversion-lead-gold-lhc
